1. Field of the Invention
The present invention relates to a golf putter used for putting, which can adjust the angle (i.e., the lie angle) formed between a putter head and a shaft.
2. Description of Related Art
There are an estimated 60 million golfers worldwide today, and golf is considered a very popular sport, particularly in developed countries. Golf is a very simple exercise in which a golfer uses fourteen golf clubs to put a golf ball into eighteen holes/cups on the green, which are approximately 10-546 yards far away from each other, through the process of hitting tee shots and approach shots. However, it is known that most golfers feel stress but not amusement when putting on the green as a finishing step in each hole. The reason for this is that the diameter of the hole is no more than 10 cm and it is difficult to set the aiming point and adjust the distance between the golf ball and the hole according to the slop of the putting green. But first of all, the reason why the golfers feel stress with putting is that since a golf putter a golfer uses does not fit the somatotype characteristics of the golfer, the direction in which a putted golf ball rolls initially toward the hole does not align with a desired direction. For example, accuracy in the directionality of a golf ball is required to be more than 99% in order to put a golf ball 5 m away from a hole into the hole even on a relatively flat putting green having no a slope. The problem associated with the putting resides in that in the case where a collision occurs between a putter head and a golf ball putted with a perfect stroke through more practice, if the putter head is not maintained in a horizontal state, the front striking surface of the golf putter is not oriented toward an aiming point set by a player, and as a result the golf ball does not roll correctly in the direction the aiming point. For example, when a player hits a putting shot three meters on the putting green having no a slope, if the putter head is aimed at the hole in a state in which a toe is lifted by 7 degrees, the slotline of the golf putter is oriented toward the hole but the front surface of the putter head confronts the left edge of the hole so that although the golf ball is rolled in a straight line, it passes by the hole. But actually, since the front surface of the golf putter is not perpendicular to the progress direction (i.e., the center of the hole) of the putter head, the golf ball upon the collision against the putter head is spinning to the side in a counterclockwise direction, and the rolling golf ball is greatly deviated from the hole in a hook shape in which the golf ball is spinning to the left as if the rolling golf ball rolled on a left downhill slope. This phenomenon very frequently occurs in most weekend golfers and many professional golfers. However, most golfers consider a cause of the phenomenon to be a problem associated with their stroke or a failure to correctly grasp the slope of the green. Of course, the lie angle of the golf putter that does not fit the somatotype characteristics of the golfer is one of various key factors that hinder the dropping of a golf ball into the hole, but also is a problem that can be solved in the easiest manner.
Nowadays, many kinds of golf putters are manufactured by numerous golf club manufacturers, but the somatotype characteristics and the putting postures of the golfers vary depending on the golfers and thus it is not easy to purchase golf putters correctly that fit their somatotype characteristics and putting postures. Furthermore, since the somatotype characteristics and the putting postures of the golfers vary over time, it is difficult to find new golf putters that fit them each time. Thus, the above-mentioned problems will be solved by a golf putter in which the angle (i.e., the lie angle) formed between a putter head and a shaft can be adjusted, if necessary. In particular, a lie angle adjustable golf putter requires that the lie angle should be adjusted only when a player desires to adjust it. In addition, the lie angle adjustable golf putter cannot be used in a formal golf game until it receives an approval from the United States Golf Association (USGA) or R&A.
Inventors have provided numerous golf putters that comply with the above purpose over the past several decades. However, most inventions related to golf putters entails a lot of problems in the actual use thereof, golfers suffer from an inconvenience in use, or the approval of the golf putters is denied by USGA or R&A. For this reason, the golf putters provided by the inventors have nearly disappeared on the market before they reach real consumers. For example, U.S. Pat. No. 5,580,051 discloses an adjustable golf club putter which comprises a putter head and a shaft interconnected by means of an adjustable gear linkage comprising a shaft gear and a hosel gear, each of which has a gear teeth, and the shaft gear and the hosel gear are engaged with or disengaged from each other by means of tightening or loosing of a bolt so as to adjust the lie angle formed between the putter head and the shaft. However, such a conventional adjustable golf club putter entails a shortcoming in that the gear linkage is large and complicated in terms of structure, and that since the adjustable lie angle has a limited range, it is not easy for a golfer to obtain a desired lie angle. U.S. Pat. No. 5,542,665 discloses an adjustable golf putter in which an angle adjustment means is connected to an adaptor interconnecting a putter head and a shaft, the adaptor being connected to a rear surface of the putter head. Since the adaptor is disposed on the rear surface, the distance between an adaptor portion connected to the shaft and a ball striking portion are longer than that in general golf putters, thus causing a problem in that a golfer must hit a putting shot pullingly but not pullingly. In addition, U.S. Pat. No. 4,815,740 discloses an adjustable golf club in which the line of the center of gravity of the golf club putter is used as an ideal axis, a circular array of V-shaped serrations is arranged on the axis, and another set of similar serrations are connected to a shaft by a hosel linkage. This configuration is theoretically excellent, but encounters a problem in that the golf club is complicated structurally due to an unnecessary part such as a compression spring, resulting in a deficiency of simplicity and practicality needed for mass production.
Accordingly, the present inventor has proposed an adjustable golf putter disclosed in U.S. Pat. No. 6,142,884 corresponding to Korean Patent Registration No. 10-0584815 in an attempt to solve the problems occurring in the existing prior arts, and receives popularity from golfers with the success in mass production of the golf putter. However, such a golf putter has a problem in that if it is used for a long period of time after adjusting and fixing the lie angle, lock screws are often loosened from the threaded holes. A lie angle adjustable golf putter requires that the adjusted lie angle of the golf putter should not be changed and a locking means for securely fixing a shaft and a putter head should not swivel the putter head in use. Particularly, in the case where the lock screws of the locking means are loosened means during the golf game to cause the putter head to be swiveled, unless a tool for tightening the lock screws is prepared, a golfer suffers from a great inconvenience.